This invention relates to anchors. More particularly, this invention relates to lightweight anchors.
A lightweight anchor is a type of anchor made up essentially of a shank, a stock, a crown and a pair of flukes. The principal feature of a lightweight anchor is its high holding power to weight ratio. The holding power of a lightweight anchor is dependent on several factors including the weight of the anchor, the shape of the flukes, the surface area (size) of the flukes, and the strength of the flukes. The strength of the flukes, that is, the resistance of the flukes to bending or failure is dependent on the type of material used in making the flukes, the thickness and design of the flukes and the manner in which the flukes are fabricated.
In the past, the flukes in a lightweight anchor have been made of a single sheet of mild steel suitably cut and shaped, or out of a casting of high strength steel or out of aluminum by extrusion. Flukes have also been made of a single sheet of stainless steel, suitably cut and shaped, but, because of the high cost of stainless steel as compared to most other steels or aluminum, stainless steel flukes have not enjoyed much commercial success. In any event, in all cases the fluke bodies have been of a unitary construction.
In U.S. Pat. No. 3,783,815 to R. C. Town et al. there is illustrated a lightweight cast steel anchor in which the flukes contain integrally formed, molded stiffening ribs to increase the strength and holding power of the anchor. Some other examples of lightweight anchors can be found in U.S. Pat. No. 3,780,688 to D. C. Hungerforth and U.S. Pat. No. 3,782,318 to D. C. Hungerforth.